The Diablo III Website announces a new Paragon system for Diablo III which will add new endgame content to Diablo III when the version 1.04 patch goes live for the action/RPG sequel, which is currently expected by the end of this month. This will add 100 paragon levels to player development with new stat and magic find rewards. There's also this forum post outlining how the auction house will be changed in the new version. Here's the outline of how the new Paragon system will work:

After you hit level 60, any further experience you earn from killing monsters will begin to count toward Paragon levels

There are 100 Paragon levels

Every Paragon level will reward you with:

Core stats such as Strength, Dexterity, Intelligence, and Vitality in amounts similar to what you’d gain from a normal level

3% Magic Find and 3% Gold Find

In addition, a distinctive increasingly-impressive border will surround your character portrait in the in-game party frame to denote your Paragon progression, with a new frame earned after every ten levels. Your Paragon level will also be visible to other players wherever your normal level is shown

If that experience chart(unofficial) is at all correct, I will never even come close to Paragon 100, or probably even Paragon 5. I do like the preview changes for the rest of patch 1.04 though, and I'll probably keep playing D3 on and off as new patches catch my eye, etc.

This paragon system isn't the worst thing that's ever been done in Diablo 3, but the sheer scope of the grind involved means it will likely have almost no actual effect on me or what gear my characters wear. My barbarian has the most MF of all my guys, at around 240% pre-NV. No danger of hitting the cap anytime soon.